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IGCSE Biology - Extended > The Endocrine System > Flashcards

The Endocrine System Flashcards

1
Q

What is the endocrine system?

A

A collection of endocrine glands found throughout the body that secrete hormones directly into the bloodstream

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2
Q

Definition of hormone

A

A hormone is a chemical substance, produced by a gland and carried by the blood, which alters the activity of one or more specific target organs

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3
Q

How does a hormone bring about a response?

A

Receptors on the cell membranes of cells in the target organ recognise the hormone.
The cells then respond by changing their cellular activity to bring about a particular effect.

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4
Q

5 differences between the endocrine and the nervous system?

A
  • transmission of chemicals / electrical impulses
  • transmission via blood / in nerves
  • slow transmission / rapid transmission
  • hormones dispersed throughout body / impulse sent directly to target organ
  • long-term effects / short-term effects
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5
Q

What is similar about the nervous and the endocrine system?

A

Can carry messages long distances in the body

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6
Q

What does the endocrine system coordinate?

A

Coordinates the activity of many different organs and bodily functions.

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7
Q

In what process does the E system play a key role in?

How?

A
  • HOMEOSTASIS

- enables cells to alter their activity in response to changes in body conditions

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8
Q

What can happen if the E system isn’t working properly?

A

Can prevent internal conditions from being regulated effectively.

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9
Q

What does the pituitary gland do?

A

Secretes several types of hormone in response to changes in body condition

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10
Q

What is special about some pituitary hormones?

A

Used to regulate the activity of other endocrine glands, which secrete the own hormones in response

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11
Q

What gland secretes adrenaline?

A

Adrenal gland

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12
Q

What parts of the body does adrenaline target?

A

Heart, blood vessels, liver

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13
Q

When is adrenaline released?

A

In times of fear or stress

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14
Q

Effects of adrenaline

A
  • increasing heart rate
  • increasing blood pressure
  • increasing blood flow to muscles
  • relaxing the airways and increased breathing rate
  • stimulating the liver to convert glycogen to glucose, which is released into the blood to increase blood glucose levels
  • pupils dilate
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15
Q

What do the effects of adrenaline increase?

A

the body’s metabolism

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16
Q

Advantages of increased heart rate and blood pressure

A

Increases the flow of blood to the muscles

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17
Q

Advantages of relaxing the airways and increasing breathing rate

A

Allows more oxygen to enter the lungs where it is taken up into the blood

18
Q

Advantages of the release of glucose from the liver

A

Increases blood glucose levels, allowing more glucose to be delivered to the muscles

19
Q

The overall advantage of adrenaline

A

Adrenaline increases the supply of oxygen and nutrients to the muscles - priming them for action

20
Q

Why is the increase of oxygen and glucose to the brain good?

A

Primes the brain for activity

- coordinating a response to the stress that has stimulated the secretion of adrenaline

21
Q

What happens after the hormones have taken action and are no longer needed?

A
  • Do not remain permanently in the blood

- changed by the liver into inactive compounds and are excreted by the kidneys

22
Q

Do endocrine glands deliver their secretion through ducts?

A

NO

- hormones picked up directly from glands by the blood circulation

23
Q

What can cause hormonal changes to be slower?

A
  • depend on the speed of circulatory system (time taken for hormone to travel)
  • time it takes for cells to change their chemical activities
24
Q

What changes can hormones cause/ take part in?

A

growth rate, puberty, pregnancy

25
Q

What is the adrenal medulla and what is its role?

A

Part of the adrenal gland

Receives nerve impulses from the brain and releases adrenaline

26
Q

What is the process that leads to adrenaline being released?

A

In response to a stressful situation, nerve impulses are sent from the brain to the adrenal medulla, which releases adrenaline into the blood

27
Q

Is the pancreas an endocrine (ductless) gland?

A

YES

28
Q

What are islets?

A

Hormone-producing cells are arranged in small isolated groups called islets

29
Q

what are exocrine glands?

A

glands which secrete substances through a duct or tube

30
Q

What do the ovaries produce?

A

oestrogen and progesterone

  • control puberty in females (make female secondary sexual characteristics develop) including development of breasts and hips.
  • control the menstrual cycle and ovulation
31
Q

What do the testes produce?

A

Testosterone

  • controls puberty in males, including deepening hair, stronger muscles and growth of body hair
  • controls development and release of sperm
32
Q

How is hormone production controlled by feedback control?

A

hormones regulate their own production

  • as the level of hormone in the blood rises, it switches off (INHIBITS) its own production so that the level never gets too high
  • as the level of hormone in the blood falls, it switches on (STIMULATES) its own production so that the level never gets too low.
33
Q

What 2 hormones secreted by the pituitary gland control the secretion of further hormones by the reproductive organs?

A

LH and FSH

34
Q

In females, what do LH and FSH stimulate the secretion of?

A

oestrogen progesterone by the ovaries

35
Q

In males, what do LH and FSH stimulate the secretion of?

A

Stimulate testes to produce testosterone

36
Q

What are the female secondary sexual characteristics?

A
  • breasts develop
  • hips widen
  • pubic hair grows
  • eggs are released
37
Q

What are the male secondary sexual characteristics?

A
  • voice deepens
  • pubic hair grows
  • facial hair grows
  • sperm are produced
38
Q

Basic summary of how reproductive hormones take part in the menstrual cycle

A

Hormones stimulate the maturation and release of an egg from the ovaries approximately every 28 days.

39
Q

Why is it important that the uterus lining thickens prior to ovulation during the menstrual cycle?

A

If an egg is fertilised, it implants itself in the uterus lining.
Uterus lining provides the fertilised egg with a supply of oxygen and nutrients, enabling it to develop into an embryo.

40
Q

What happens if an egg is not fertilised?

A

Uterus lining breaks down and the menstrual cycle begins again.

IGCSE Biology - Extended (22 decks)

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